Animals, particularly animals in the wild, have long been injected with tranquilizers and other drugs through the use of hypodermic darts propelled by means of a rifle or similar device. Such darts are constructed to lodge into the skin of the animal and to release their drug charge upon impact. The dart needs to be removed from the animal shortly after use, in order to avoid infection or other injury to the animal.
On the other hand, the need often exists to provide drug treatment to an animal over extended periods of time. Moreover, the drug may be of a type, such as a somatotropin, which would be broken down by the animal's digestive system if administered with its food supply. U.S. Pat. No. 5,266,325 granted to Kuzma et al. on Nov. 30, 1993 suggests that drugs which need to be administered over an extended period of time be provided in a sustained release drug-delivery implant which is injected subcutaneously into the living tissues of the subject. In accordance with Kuzma et al., the implant is introduced into the subject through a cannula of a large hypodermic needle/syringe-like instrument, which is removed from the subject's body immediately after injecting the implant. However, this method of introducing drugs is unsatisfactory for treating large groups of animals. For example, when treating cattle or pigs in the field, it would not be convenient to sterilize the hypodermic needle or to use a new needle for each animal. The danger therefore exists that a needle contaminated by one animal could infect an entire group.
Another shortcoming of utilizing implants is that they tend to shift in position. It therefore becomes very difficult, if not impossible, to detect whether a subject has or has not received an implant. Kuzma et al. suggests using a radioactive material within the implant to permit detection. However, in the field, this is not a satisfactory solution.
Broadly, it is an object of the present invention to provide a system for introducing sustained release implants into animals, which system avoids the shortcomings of known systems of this type. It is specifically contemplated that the system be capable of introducing implants to a large group of animals without the risk of spreading infection or disease among them.
It is another object of the invention that drug containing implants introduced into an animal be capable of remaining within the animal for extended periods of time, while their presence or the fact of their having been introduced is readily detectable, despite the depletion of the drug, and without the use of complex instruments.
It is yet another object of the present invention to inject implants containing one or more drugs into a subject animal without the need to invasively penetrate the bodies of multiple animals with a common instrument.
It is also an object of the present invention to provide a system and apparatus for introducing drug containing implants into the body of a subject, which system and apparatus are simple, convenient, and reliable in use, yet relatively inexpensive in construction.
In accordance with the present invention a dart containing drug-delivery implants is provided, which can be introduced and implanted readily in the subject's body at a given site, for example, subcutaneously in a pig's ear, without the use of an instrument which invades the subject's body.
In accordance with a preferred embodiment of the invention, the dart is of plastic material having a hollow cylindrical body and a solid head, generally of a cylindrical shape. The face of the dart head has a scoop shape and the exposed edge surface of the face has a fillet radius that starts at the top edge of the dart body and tapers downwardly and forward from the hollow body. This forms a relatively long narrow blade at the lower part of the head, the leading edge of which is formed with a sharp chisel point, to provide for penetration entry of the dart into the subject's body.
Flexible stabilizing wings are provided on either side of the dart head. The stabilizing wings sweep outwardly and backward toward the hollow cylindrical body and serve as a lock or barb to prevent the dart from being pulled out of the subject once it has entered the subject's body part.
The dart's hollow body is preferably a coil of material formed with a number of turns into a helix. This gives the body a degree of flexibility to permit the dart's body shape to change as it conforms to the darted site of the subject's body. The coil also makes the dart body compressible in a lengthwise direction, to provide rigidity as the dart is inserted under pressure into the subject. One or more implants, which may contain the same or different substances, are located within the hollow body. There is a passage through the dart head into the body to provide fluid communication between the subject's body fluids and the implant. An end cap is frictionally fitted into an opening at the rear of the body. The presence of the dart injected into the subject may be determined visually or by palpation of the subject's darted body part (e.g. the ear).
It is a feature of the invention that a dart which is pervious to body fluids is provided which carries implants containing one or more substances and that the dart is itself implanted directly into a subject, such as a pig.
A further feature of the invention is that a dart for carrying one or more implants is pervious to body fluids and includes a head with a blade having a sharp tip for penetrating the subject's body. The dart body contains one or more implants with substances to be released into the subject, so that the dart is readily injected into the subject and carries the implants with it.
It is yet another feature of the invention that a dart for carrying one or more implants into a subject is pervious to body fluids and has a body which is firm and rigid while being inserted into the subject, yet may expand in its lengthwise direction, to become flexible after insertion into the subject.
It is a further feature of the invention that the presence within a subject's body part of an injected dart containing drug-delivery implants may readily be determined visually or by palpation of the subject's body part.